Method and system for shortening the length of time gaps between data units in a data switching network

ABSTRACT

A group of K data units received consecutively is arranged by a first device. The arranged K data units are sent to the inputs of M devices, and a group of H j  data units of the arranged K data units are transferred by a device j of the M devices. The data units sent to the devices of the M devices are arranged such that no two inputs of the devices of the M devices transferring receive the same data unit at any moment. A second device combines and arranges the K data units from the outputs of the M devices such that the K data units appear at the output of the second device consecutively, and a length of time gap between data units in a data switching network is shortened.

CROSS-REFERENCE TO RELATED PATENT APPLICATIONS

This application is a Continuation of U.S. application Ser. No.12/277,028, filed Nov. 24, 2008, which claims priority to U.S.Provisional Application No. 60/996,584, which was filed on Nov. 26,2007, and are herein incorporated by reference.

FIELD

The present disclosure relates generally to the field of wirelesscommunications, and more specifically to ultra-wideband wirelesscommunication that employs several communication parameters.

BACKGROUND

Devices and methods have throughout been developed for the efficienttransfer of data messages from one distance to another. The exponentialgrowth in the volume of data message transfer led to the development ofswitching, effectively allowing multiples of data messages to bedelivered over common lines.

Innovation eventually led to optical networks, which are shown to besuitable for providing the required transmission bandwidth for therapidly growing communication traffic of present day.

Switching technology has likewise progressed. Packet switching has beenwidely considered as a successful approach to efficiently deal with theproblem of transporting bursty data traffic. In packet switchednetworks, data streams are broken up into small packets of data. Thesesmall packets are multiplexed together with packets from other datastreams inside a network. The packets are exchanged inside the networkbased on their destinations. To facilitate switching, a packet header isadded to the body, i.e. “payload”, in each packet. The header carriesaddress information, for example, the destination address or the addressof the next node in the path. The intermediate nodes read the header anddetermine where to forward the packet based on the information containedin the header. At the destination, packets belonging to a particularstream are received and the data stream is put back together. Thepredominant example of a packet-switched network is the Internet, whichuses the Internet Protocol (IP) to route packets from their source totheir destination. Packet switching may be one of the most importantdata transportation methods for furthering optical networks.

One problem in implementing a packet switched optical network is thedifficulty of guaranteeing high bandwidth utilization, i.e., packetexchange rate and link utilization, when the fiber transmission rate ishigh. In an optical network node, optical switches are the devices toexchange packets between inputs and outputs of the node. Occasionally,optical switches require reconfiguration for the packet exchange.Although fast all-optical switching technologies have been demonstratedrecently, fast optical switches with a switch reconfiguration time innanoseconds or picoseconds range are only available in smaller sizes,such as 2×2. Large optical switches with up to a thousand ports havebeen demonstrated using the micro-electro-mechanical systems (MEMS)technology but the required switch reconfiguration time is inmilliseconds (Kim et al. “1100×1100 part MEMS-based optical crossconnectwith 4-dB maximum loss”, IEEE Photonics Technology Letters, Vol. 5, No.11, PP. 1537-1539, 2003). Although a multi-stage approach has beencommonly used to build large electrical switches from small switches,the rapid accumulation of optical loss through the stages and the highinterconnection complexity make it impractical for optical switches.

In the packet transmissions, a guard time (T_(g)) between packets isrequired to prevent packets from interfering with each other. Inexisting packet switches, packet-by-packet switching approach is used.The T_(g) must be larger than the reconfiguration time (T_(sw)) of theswitches that exchange the packets, i.e., the T_(g) between packets hasto be sufficiently large to prevent packets from being accidentallydiscarded in the switch. Since no data transmission can be taken duringthe period of T_(g), low transmission bandwidth utilization will beobtained if the T_(g) is large. Owing to the lack of large, fast opticalswitches, some approaches such as optical burst switching (OBS) tend toassume very large data packets for reasonable transmission bandwidthutilization (Qiao et al. “Optical burst switching (OBS)—a new paradigmfor an optical Internet”, Journal of High Speed Networks, Vol. 8, pp69-84, 1999.) Since one cannot lengthen the packets by too much, theswitch reconfiguration time will become increasingly significant indetermining the transmission bandwidth utilization, unless we can reducethe switch reconfiguration time in proportion to the increase in thefiber transmission rate, or relax the constraint imposed on the packetguard time T_(g) by switching fabric reconfiguration time T_(sw).

It is an object of the present invention to overcome the disadvantagesand problems in the prior art.

SUMMARY

In a first preferred aspect, there is provided a method for shorteningthe length of time gaps between data units in a data switching network;the method comprising:

arranging a group of K data units received consecutively at an input ofa first device in K time units, where K is a positive integer;

sending the arranged K data units to the inputs of M devices, where M isa positive integer;

transferring a group of H_(j) data units of the arranged K data units bya device j of the M devices from its inputs to its outputs within a timeunit T_(x) in the K unit time period, where H_(j) is a positive integerand the sum of H_(j) for j=1, . . . M is equal to K, where H_(j)≦K;

arranging the data units sent to the devices of the M devicestransferring at time unit T_(x), such that no two inputs of the devicesof the M devices transferring at time unit T_(x) receive the same dataunit at any moment; and

repeatedly combining and arranging the K data units from the outputs ofthe M devices by a second device such that the K data units appear atthe output of the second device consecutively.

The data switching network may be a slotted network.

Each data unit may be a sequence of data bits whose total transmissiontime is smaller than a unit of time.

The data unit may not contain any information of the path to thedestination of the data unit.

The data unit may contain dummy bits that do not carry information, anda period of time without signal transmission is considered as a sequenceof dummy bits.

The data switching network may be a packet switching network.

Each data unit may be a packet which contains header and payload, theheader having information indicating the path to the destination of thepacket.

The data switching network may be an optical network.

The first device may be an optical splitter or an optical switch, with Koutputs connecting to the inputs of the M devices such that K data unitsare sent to the M devices for each K unit time period.

The method may further comprise adding an optical delay element beforethe first device such that the K data units are delayed before enteringthe first device.

The method may further comprise adding an optical delay element afterthe outputs of the first device and before the inputs of the M devicessuch that the K data units are delayed before entering the M devices.

The optical delay elements at the inputs of the devices of the M devicesmay be transferring data units within the same predefined time unitT_(x) have different delay values such that no two inputs of the devicesreceive the same data unit at any time.

The second device may be an optical combiner or an optical switch with Kinputs connecting to the outputs of the M devices such that the K dataunits are combined and sent via the output of the second deviceconsecutively.

The method may further comprise adding optical delay elements at theoutputs of the M devices such that the K data units are delayed beforeentering the inputs of the second device.

The delay elements at the outputs of the M devices may have differentdelay values such that the K data units from the outputs of the Mdevices appear consecutively at the output of the second device.

The method may further comprise connecting a pilot message channel to athird device to describe the K data units sent to the inputs of the Mdevices such that the M devices are configured by the third devicebefore the arrival of the K packets.

The optical delay elements are variable and fixed delay value opticalfiber delay lines.

The device j may be an optical switch with reconfiguration time notlarger than K-1 time units.

K may be greater than one.

In a second aspect, there is provided a system for shortening the lengthof time gaps between data units in a data switching network; the systemcomprising:

a first device having an input receiving an arranged group of K dataunits consecutively in K time units, where K is a positive integer;

M devices having inputs to receive the arranged K data units, where M isa positive integer;

a device j of the M devices to transfer a group of H_(j) data units ofthe arranged K data units from its inputs to its outputs within a timeunit T_(x) in the K unit time period, where H_(j) is a positive integerand the sum of H_(j) for j=1, . . . M is equal to K, where H_(j)≦K;

wherein the data units sent to the devices of the M devices transferringat time unit T_(x) are arranged such that no two inputs of the devicesof the M devices transferring at time unit T_(x) receive the same dataunit at any moment; and

repeatedly combining and arranging the K data units from the outputs ofthe M devices by a second device such that the K data units appear atthe output of the second device consecutively.

Another aspect of the invention comprises a method for shortening thelength of time gaps between data units in a data switching network. Themethod includes arranging a group of K data units received consecutivelyat an input of a first device in a time period of length L, where K is apositive integer and L is a positive real number, sending the arranged Kdata units to the inputs of M devices, where M is a positive integer,transferring a group of H_(j) data units of the arranged K data units bya device j of the M devices from its inputs to its outputs within a timeperiod T_(j) of length L_(j), where H_(j) is a positive integer and thesum of H_(j) for j=1, . . . M is equal to K, where H_(j)≦K, and L_(j) isa positive real number, where L_(j)≦L for j=1, . . . M, arranging thedata units sent to the devices of the M devices transferring at timeperiod T_(j) such that no two inputs of the devices of the M devicestransferring at time period T_(j) receive the same data unit at anymoment for j=1, . . . M, and repeatedly combining and arranging the Kdata units from the outputs of the M devices by a second device suchthat the K data units appear at the output of the second deviceconsecutively.

The present invention relates to optical switches and architectures, andmethods for their use, for the transmission of packets over a network.Through the invention, optical packet switches with very highutilization of transmission bandwidth are presented.

The invention first divides a packet stream into multiple packetsub-streams and then sends the packets of the sub-streams to theswitching fabrics in the optical switches. After the division of thepacket stream into packet sub-streams, time gaps with duration ofmultiple packet transmission time are generated between the packets inthe same sub-streams. These time gaps can be used for thereconfiguration of the switching fabrics. Consequently, thereconfiguration time of the switching fabrics is only required to besmaller than the minimum of the time gaps of the packet sub-streams andis no longer necessary to be smaller than the packet guard time in theoriginal packet stream. Since packets typically have length of kilobytesor more, we can use switching fabrics with reconfiguration time at leastthousands of times that normally required for optical packet switching.After the packets have been transferred to the required outputs of theswitching fabrics, we can have a single signal stream by merging thepackets from the corresponding outputs of the switching fabrics.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects, and advantages of the apparatus andmethods of the present invention will become better understood from thefollowing description, appended claims, and accompanying drawings where:

FIG. 1 shows a block diagram of the method of switching performed by thepresent switches; and

FIG. 2 shows an embodiment of an optical switch of the presentinvention;

FIG. 3 shows an embodiment of the present switch wherein multiple switchfabrics are utilized;

FIG. 4 shows another embodiment of the present switch, wherein theswitch further includes a switching control processor;

FIG. 5, with reference to Example 1, shows the transfer of packetsthrough the present switch in FIG. 2;

FIG. 6, with reference to Example 1, shows the transfer of packetsthrough the present switch in FIG. 3;

FIG. 7, with reference to Example 1, shows the transfer of packetsthrough the present switch in FIG. 4.

DETAILED DESCRIPTION

The following description of certain exemplary embodiment(s) is merelyexemplary in nature and is in no way intended to limit the invention,its application, or uses. Throughout this description, the term “signal”shall refer to a digital or analog indicator whether cohesive ornon-cohesive, mechanical, electrical, or optical in nature, thatpossesses data. The term “optical splitter” shall refer to a devicecapable of splitting, duplicating, or copying an optical signal toresult in two or more optical signals of equal or varying strength. Theterm “optical multiplexer” shall refer to a device capable of acceptingmultiple optical signals and combining them into one signal.

FIG. 1 shows a block diagram of the general method of the invention forswitching packets consecutively received from a signal stream. Examplesof different implementation of the method are shown in FIGS. 2-4.

In 101 of FIG. 1, a signal stream is received, and is sent to asplitter. The splitter splits the power of the signal and duplicatesmultiple copies (sub-streams) of the signal stream at its outputs in105. If K copies of the signal stream have been duplicated, inprinciple, we can fully recover the information of the original signalstream by only retrieving 1/K information of each duplicated signalstream. Hence, (K-1)/K of the time period of each duplicated signalstream will be available for the switch reconfiguration if we haveproperly arranged the packets in the duplicated signal streams. In 110,a period of time in a duplicated signal stream is reserved and is usedas the time gap for the reconfiguration of the switching fabric whichtransfers the packets of the duplicated signal stream. A switchingfabric is the module used in an switch that transfers the packetsbetween the inputs and outputs of the switch. Apart from reserving thetime gap, we also need to properly arrange (synchronize) the packetsfrom different duplicated signal streams so that the switching fabricscan correctly transfer the packets. In 115 of FIG. 1, the packets ofdifferent duplicated signal streams are properly synchronized beforebeing sent to the switching fabrics. When the packets of the duplicatedsignal streams arrive at the inputs of the switching fabrics connectingto the splitter, the switching fabrics have already completed therequired reconfiguration because of the sufficiently large time gapsbetween the packets. In 120 of FIG. 1, the packets of the duplicatedsignal streams are therefore sent to the required outputs of theswitching fabrics. Note that the reconfiguration time of the switchingfabrics must be smaller than the time gaps between the packets of theduplicated signal streams. After the packets have been transferred tothe required outputs of the switching fabrics, we have to combine andmerge the packets from different outputs of the switching fabrics into asingle signal stream. Hence, the packets are first synchronized in 125of FIG. 1 and then combined and merged into a single signal stream in130 of FIG I.

FIG. 2 is an embodiment of an optical switch 200 of the presentinvention. This is an implementation of the general method shown in FIG.1.

In the optical switch 200, input signals 201 are delivered to the switch200 and output signals 215 are delivered therefrom. The number of inputsignals 201 can range from 1 to N, where N can be any positive number.An optical splitter 203 is utilized to duplicate the input signal 201into “K” number of signals. As known in the art, this can beaccomplished by tapering the input signal in a funnel type shapeconnecting the large input signal to smaller signals. An example ofsuitable optical splitters includes those taught in U.S. Pat. No.7,266,277, incorporated herein by reference.

In this and other embodiments, “K” number of signals refers to thenumber of outputs delivered from the optical splitter to the switchingfabric. “K” can be any number so long as the value is greater than theratio of reconfiguration time and transmission time to packet guard timeand transmission time.

Delay elements, such as fiber delay lines 205 can be employed in theswitch. Suitable fiber delay lines include fiber collimators reflectionelements, such as mirrors or prisms. Examples of fiber delay linesinclude commercial models from SANTEC Corp. of Hackensack, N.J. andGeneral Photonics Corp. of Chino, Calif.

Other embodiments include fiber delay lines having a plurality ofoptical fibers, each having a unique predetermined optical length. Fiberdelay lines taught in European Patent No. EP1099965, incorporated hereinby reference, are suitable.

The optical signals in the fiber delay lines 205 are delayed D_(k),where k=1, 2, 3, . . . K. The delayed input signals are to be sent toswitching fabric 209 via inputs 1_(i,k) 208, where i=1, . . . N and k=1,2, 3, . . . K. In one embodiment, the switching fabric 209 isnon-blocking. As known in the art, the switching fabric 209 isnonblocking if any unused input port can be connected to any unusedoutput port. The non-blocking switch is capable of realizing everyinterconnection pattern between the inputs and the outputs. Commerciallyavailable non-blocking optical switches, such as those of Glimmerglass®(Hayward, Calif.) are suitable for use herein. The switching fabric canbe a NK×NK optical switch, where N is the number of input signals.

Signals are then passed through the delay lines 211, recombined via anoptical multiplexer 213, and sent out through optical lines 215.

While not to be bound by theory, the optical splitter 203 and the fiberdelay lines 205 convert the original packet stream into multiple packetsub-streams such that packets from the input signal 201 will appearsequentially on the inputs 1_(i,k) 208 to the switching fabric 209.Therefore, a new set of input packets is presented to the switchingfabric 209 every K time slots. The switching fabric 209 is arranged totransfer a packet during rounds of K time slots, allowing at least K-1time slots for reconfiguration.

FIG. 3 is another embodiment of the switch of the present invention,wherein “K” or more switching fabrics are utilized as opposed to the oneswitching fabric in switch 200. This is another implementation of thegeneral method shown in FIG. 1

In FIG. 3, input signals 301 are firstly delayed 303, and then passed toan optical splitter 305. The split signals are then passed to the inputsof switching fabrics 1_(i,k) 307 where i=1, . . . N, k=1, 2, 3, . . . K.The switching fabrics 309 are preferably non-blocking.

The optical signals from the switching fabric outputs O_(i,k) 311 arerecombined via an optical multiplexer 313, followed by passage to theoptical lines 315, where i=1, . . . N, k=1, 2, 3, . . . K.Theoretically, while one switching fabric 309 is in reconfiguration, theother switching fabrics 309 freely transfer packets. Hence, the time ofthe packet transmissions at the other switching fabrics becomes theavailable time for a switching fabric configuration, if it is scheduledproperly.

FIG. 4 is a further embodiment of a switch of the present invention,wherein the switch 400 further includes a switching control processor(SWCP) 409. This is also another implementation of the general methodshown in FIG. 1.

As in FIG. 4, this embodiment exhibits “K” or more switching fabrics407, fed by optical splitters 405. The switching fabrics 407 no longerread the packet address information from the input signals 401, ratherthe SWCP 409 takes over the packet output lookup operations and readsthe packet address information from the control channels 415. Oncehaving completed the packet output lookup, the SWCP 409 sends pilotmessages to control channel 417 to inform the subsequent nodes about thepackets sent to outputs. Following combination by the opticalmultiplexer 411, the signals are sent to optical lines 413.

Example 1

FIGS. 5-7 show examples of the passage of packets through the presentswitches. In the examples, the “K” value is 3.

FIG. 5 shows the timing diagram for the packet transfer at the inputlink 1₁ 501 of the switching fabric of a 2×2 optical switch 500 asexhibited in FIG. 2, with K=3, where T_(d) 503 is a packet transmissiontime, T_(g) 505 is the required guard time for preventing crosstalkbetween packets, T_(cp), 507 is the required time for looking up theoutput of an incoming packet, and T_(sw), 509 is the requiredreconfiguration time for the switching fabric. A slot time T_(slot) isequal to T_(d)+T_(g). We assume that the output lookup operation onlyrequires the information of the packet address and is independent of theswitching fabric's status. The switching fabric can transfer packetsbetween its inputs and outputs even if the switch is looking up theoutputs for new input packets. However, no packet transfer at theswitching fabric is possible during the switch reconfiguration durationT_(sw). Hence, the switch can transfer 2K packets per each time periodof T_(sw)+T_(d) if we have properly arranged the packet transfer andoutput lookup operations. We assume that the switch immediately detectsthe packet address when a packet arrives at input link 1₁.

Packet 1 511 arrives at the input link 1₁ at time to when the system isidle. Because of the finite switch reconfiguration time(T_(cp)+T_(sw)=1.7 time slots (T_(slot))), the switch is not able todirectly transfer packets from 1₁. The incoming packets are delayed byD₁, D₂ and D₃ 513 when they are sent to the inputs 1_(1,1), 1_(1,2) and1_(1,3) of the switch, respectively. After reading the address of packet3 514 at time t₁, the switch starts to configure the switching fabric toprepare for packet transfer at time t₂=t_(o)+D₃−T_(sw). The packets 1,2, and 3 are finally transferred to the switch outputs in time durationt₂ to t₃ after the completion of the switching fabric internal pathsetup. It is observed that the switch can also start the switchingfabric internal path configuration at time (t_(o)+D₂−T_(sw)) or(t_(o)+D₁−T_(sw),) instead with one or two empty output slots in theinitial round of packet transfer. The average added packet delay,however, remains unchanged. The switch reads the packet 6 515 for thenext round of the packet transfer process at time t₅ and starts theswitching fabric reconfiguration at time t₆. The switching fabric istherefore idle for a period of T_(idle) 517 between the tworeconfigurations. T_(idle) is smaller than a slot time T_(slot) andshould be minimized for transmission bandwidth efficiency.

FIG. 6 shows the time diagram for the packets at input link 1₁ 601, atinputs 1_(1,1) to 1_(1,3) 603, and outputs O_(1,1) to O_(1,3) 604 of theswitching fabrics of a 2×2 optical switch 600 as exhibited in FIG. 3,when K is 3. In FIG. 6, we assume that the total time required forpacket output lookup and switching fabric reconfiguration is also equalto 1.7 time slots, i.e., T_(cp)+T_(sw)=1.7 T_(slot). We also assume thatall switching fabrics 309 detect the packet addresses at the input link1₁ 601. However, the switching fabrics 309 are scheduled to operate insequence such that switch fabric k 309 only starts its packet outputlookup and reconfiguration at packets 3Z+k, where Z is a non-negativeinteger and k=1, . . . , 3. For example, switching fabric 1 only takescare of the packets 1, 4, 7, . . . as shown in the FIG. 6. We assumethat the packet transfer delay from the inputs to outputs of a switchingfabric is negligible.

A packet 1* 607 (it may be a new packet, or a packet come from inputsI_(1,1) or I_(2,1)) is sent out to output 01,1 604 during time period t1to t2. The switching fabric 1 309 then waits until time t₃ and takes(T_(cp)+T_(sw)) time for the packet output lookup and internal pathreconfiguration to transfer packet 4* 609 to output O_(1,1) at time t₅.During the time period t₂ to t₅, switching fabrics 2 and 3 309 processthe input packets 2 and 3 and transfer packets 2* 611 and 3* 615 tooutputs O_(1,2) and O_(1,3) in sequence. Similarly, switching fabrics 3and 1 309 will transfer packets 3* 615 and 4* 609 to outputs O_(1,3) andO_(1,1) 604 during the reconfiguration of switching fabric 2 309. As theswitching fabrics 309 shift their operations in sequence, the switch 300of FIG. 3 can non-interruptedly transfer packets between its inputs andoutputs. Similar to that of the KN×KN switching fabric 209 of FIG. 1,each N×N switching fabric 309 of FIG. 3 needs to reconfigure itself perK packet transmission times.

FIG. 7 is the timing diagram for the packets at input link 1₁, at inputs1_(1,1) to 1_(1,3), outputs O_(1,1) of the switching fabric, and thepilot messages at control channels C_(in-1), and C_(out-1) of the 2×2optical switch 700 as exhibited in FIG. 4 when K is 3.

The pilot message 1 701 arrives at time t_(o). The switching controlprocessor 35 (SWCP) 409 takes T_(cp) time to look up the output andtherefore the switching fabric 407 starts the internal pathreconfiguration at time t₁. To compensate the pilot message processingtime at the SWCP, the fiber delay lines 403 at each input link I_(I) hasdelay value of D 702 that is not smaller than T_(cp). Although the timeis at t₁, the SWCP processor already has the complete information of thewhole switch in the coming T_(offset) time, e.g., the packet 1* 705 willbe sent to output O_(1,1) 706 at time t₂. If packet 1* 705 is a newpacket, it is assumed assume that it is delayed at least (T_(cp)+T_(sw))time before its injection to the switch, i.e., packet 1* has to arriveat the switch before time t_(o) such that the SWCP processor willinclude it in the output assignment at t1. Hence, the SWCP processorsend out the pilot message 1* 703 to the control channel C_(out-1) 711at time t₁ without waiting for the completion of the switching fabricreconfiguration. With the assumption of using the same routing paths oftheir associated packets, pilot messages will arrive at the subsequentnodes T_(offset) time ahead, and the subsequent nodes can pre-configuretheir switching fabrics accordingly.

Both switch architectures of FIGS. 2 and 3 need no pilot messages and itis feasible to use switching fabrics of different reconfiguration timesin different nodes. In spite of the inflexibility in the sourcing ofswitching fabric, the switching approach of FIG. 4 can embed the pilotmessages into the earlier arriving packets, e.g., pilot messages 3 and 4can be carried in packets 1 and 2.

Having described embodiments of the present system with reference to theaccompanying drawings, it is to be understood that the present system isnot limited to the precise embodiments, and that various changes andmodifications may be effected therein by one having ordinary skill inthe art without departing from the scope or spirit as defined in theappended claims.

In interpreting the appended claims, it should be understood that:

(a) the word “comprising” does not exclude the presence of otherelements or acts than those listed in the given claim;

(b) the word “a” or “an” preceding an element does not exclude thepresence of a plurality of such elements;

(c) any reference signs in the claims do not limit their scope;

(d) any of the disclosed devices or portions thereof may be combinedtogether or separated into further portions unless specifically statedotherwise; and

(e) no specific sequence of acts or steps is intended to be requiredunless specifically indicated.

1. A non-transitory computer-readable medium having instructions storedthereon that, when executed by a computing device, cause the computingdevice to perform operations comprising: arranging a group of K dataunits received consecutively at an input of the computing device in atime period of K units, wherein K is a positive integer, and wherein atime period of one unit is a period of time necessary for receiving onedata unit at the input of the computing device; and sending the arrangedK data units to the inputs of M devices, wherein M is a positiveinteger, wherein a group of H_(j) data units of the arranged K dataunits are transferred by a device j of the M devices from its inputs toits outputs within a time period T_(x), wherein the time period T_(x) isless than or equal to one unit, and wherein H_(j) is a positive integerand the sum of H_(j) for j=1 . . . M is equal to K, where H_(j)≦K; andarranging the data units sent to the devices of the M devicestransferring during the time period T_(x) such that no two inputs of thedevices of the M devices transferring during the time period T_(x)receive the same data unit at any moment, wherein a second devicecombines and arranges the K data units from the outputs of the M devicessuch that the K data units appear at the output of the second deviceconsecutively, and a length of time gap between data units in a dataswitching network is shortened.
 2. The non-transitory computer-readablemedium of claim 1, wherein the data switching network is one of aslotted network, a packet switching network, or an optical network. 3.The non-transitory computer-readable medium of claim 1, wherein thecomputing device is an optical splitter or an optical switch, with Koutputs connecting to the inputs of the M devices such that K data unitsare sent to the M devices for each K unit time period.
 4. Thenon-transitory computer-readable medium of claim 1, wherein the K dataunits are delayed before entering the computing device by an opticaldelay element before the computing device.
 5. The non-transitorycomputer-readable medium of claim 1, wherein the K data units aredelayed before entering the M devices by an optical delay element afterthe outputs of the computing device and before the inputs of the Mdevices.
 6. The non-transitory computer-readable medium of claim 5,wherein the optical delay elements at the inputs of the devices of the Mdevices are transferring data units within the same predefined time unitT_(x) have different delay values such that no two inputs of the devicesreceive the same data unit at any time.
 7. The non-transitorycomputer-readable medium of claim 1, wherein the second device is anoptical combiner or an optical switch with K inputs connecting to theoutputs of the M devices such that the K data units are combined andsent via the output of the second device consecutively.
 8. Thenon-transitory computer-readable medium of claim 7, wherein the K dataunits are delayed before entering the inputs of the second device byoptical delay elements at the outputs of the M devices, and the delayelements have different delay values such that the K data units from theoutputs of the M devices appear consecutively at the output of thesecond device.
 9. The non-transitory computer-readable medium of claim1, wherein a pilot message channel connected to a third device describesthe K data units sent to the inputs of the M devices such that the Mdevices are configured by the third device before the arrival of the Kpackets.
 10. The non-transitory computer-readable medium of claim 1,wherein the K time units required for the computing device to receivethe K data units comprise a time period of length L, where L is apositive real number.
 11. A system comprising: a first devicecomprising: an input configured to receive an arranged group of K dataunits consecutively in a time period of K units, wherein K is a positiveinteger, and wherein a time period of one unit is a period of timenecessary for receiving one data unit at the input of the first device;and one or more processors configured to: send the arranged K data unitsto the inputs of M devices, wherein M is a positive integer, wherein agroup of H_(j) data units of the arranged K data units are transferredby a device j of the M devices from its inputs to its outputs within atime period T_(x), wherein the time period T_(x) is less than or equalto one unit, and wherein H_(j) is a positive integer and the sum ofH_(j) for j=1 . . . M is equal to K, where H_(j)≦K; and arrange the dataunits sent to the devices of the M devices transferring during the timeperiod T_(x) such that no two inputs of the devices of the M devicestransferring during the time period T_(x) receive the same data unit atany moment, wherein a second device combines and arranges the K dataunits from the outputs of the M devices such that the K data unitsappear at the output of the second device consecutively, and a length oftime gap between data units in a data switching network is shortened.12. The system of claim 11, wherein the data switching network is one ofa slotted network, a packet switching network, or an optical network.13. The system of claim 11, wherein the first device is an opticalsplitter or an optical switch, with K outputs connecting to the inputsof the M devices such that K data units are sent to the M devices foreach K unit time period.
 14. The system of claim 11, wherein the K dataunits are delayed before entering the first device by an optical delayelement before the first device.
 15. The system of claim 11, wherein theK data units are delayed before entering the M devices by an opticaldelay element after the outputs of the first device and before theinputs of the M devices.
 16. The system of claim 15, wherein the opticaldelay elements at the inputs of the devices of the M devices aretransferring data units within the same predefined time unit T_(x) havedifferent delay values such that no two inputs of the devices receivethe same data unit at any time.
 17. The system of claim 11, wherein thesecond device is an optical combiner or an optical switch with K inputsconnecting to the outputs of the M devices such that the K data unitsare combined and sent via the output of the second device consecutively.18. The system of claim 17, wherein the K data units are delayed beforeentering the inputs of the second device by optical delay elements atthe outputs of the M devices, and the delay elements have differentdelay values such that the K data units from the outputs of the Mdevices appear consecutively at the output of the second device.
 19. Thesystem of claim 11, wherein a pilot message channel connected to a thirddevice describes the K data units sent to the inputs of the M devicessuch that the M devices are configured by the third device before thearrival of the K packets.
 20. The system of claim 11, wherein the K timeunits required for the first device to receive the K data units comprisea time period of length L, where L is a positive real number.